1. Field of the Invention
The invention relates generally to processes and apparatus for treating surfaces of wafer-shaped articles, such as semiconductor wafers, wherein one or more treatment liquids are dispensed onto a surface of the wafer-shaped article.
2. Description of Related Art
Semiconductor wafers are subjected to various surface treatment processes such as etching, cleaning, polishing and material deposition. To accommodate such processes, a single wafer may be supported in relation to one or more treatment fluid nozzles by a chuck associated with a rotatable carrier, as is described for example in U.S. Pat. Nos. 4,903,717 and 5,513,668.
Alternatively, a chuck in the form of a ring rotor adapted to support a wafer may be located within a closed process chamber and driven without physical contact through an active magnetic bearing, as is described for example in International Publication No. WO 2007/101764 and U.S. Pat. No. 6,485,531.
In either type of device, process liquids are dispensed onto one or both major surfaces of the semiconductor wafer as it is being rotated by the chuck. Such process liquids may for example be strong oxidizing compositions such as mixtures of sulfuric acid and peroxide for cleaning surfaces of the semiconductor wafer. Such process liquids typically also include deionized water to rinse the wafer between processing steps, and the deionized water is commonly supplemented with isopropyl alcohol to reduce the surface tension of the rinse liquid on the wafer.
As the dimensions of the semiconductor devices formed on these wafers continue to decrease, new demands are made on the equipment for processing the wafers. Smaller device structures are more susceptible to “pattern collapse” when the surface tension of the rinse liquid or other processing liquid on the wafer is too great, a problem which arises from not only the reduced device dimensions but also from the typically higher aspect ratios that accompany smaller device structures.
These problems are exacerbated by the concurrent trend of increasing wafer diameter. Fabrication plants designed for semiconductor wafers of 200 mm diameter are increasingly giving way to those utilizing semiconductor wafers of 300 mm diameter, and development for the next generation of 450 mm wafers in underway. As the process liquids travel across larger wafer diameters, the potential increases for variations in the temperature and viscosity of the liquid as a function of distance from the point of dispensing, which can lead to inconsistent process performance.
Conventional wafer processing devices have included dispensing nozzles mounted on a swinging boom arm, so that the point of dispensing can be moved across the surface of the wafer, and have also included plural movable nozzles and showerheads as shown for example in U.S. Pat. Nos. 6,834,440 and 7,017,281 and U.S. Published Patent Appln. No. 2006/0086373. However, these approaches do not necessarily afford sufficient control over the behavior and physical properties of the liquid across the wafer surface.